JP2002098589A - Method and device for color correction - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce variation in quality of a printed matter by correcting mixing ratio of a coloring liquid to provide a color of a printed matter which is previously OKed when color change on a printed matter is detected. SOLUTION: Liquid monitoring parts 6a-6d irradiate light to a print ink A extracted from a vessel and then measures spectral characteristics of its transmission light. A printed matter monitoring part 5 measures a spectral reflectance of the print ink A printed on a print sheet 4. A calculation control part 7 calculates a color value from the spectral reflectance and judges presence of change in the color value from a previously OKed printed matter. If it is judged that the color value changed, the liquid monitoring part calculates an additional correction amount ΔCi for a mixing ratio of the print ink A in the vessel to provide the color of the previously OKed printed matter based on the value of a spectral transmissivity T (λ). A base ink or a reducer is supplied in the vessel according to an additional weight ΔWi calculated in accordance with the ΔCi.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to, for example, the measurement of the color of a colored liquid for printing (an example is ink except for special cases) and the color of a printed matter in the printing field. The present invention relates to a color correction device and a color correction method capable of correcting a compounding amount of a coloring liquid so that a color difference of a printed material becomes equal to or less than a control value when a color difference of the color of the printed material is equal to or larger than a control value with respect to a color of the previous print.

[0002]

2. Description of the Related Art Conventionally, for example, in a printing process using a coloring liquid such as ink, paint, plastic or the like, when a coloring liquid contained in a container is repeatedly printed on a continuously supplied printing sheet, visual or The color of a printed printing sheet (hereinafter referred to as a printed matter) is managed by colorimetry, and the quality of the printed matter is kept constant.

[0003] Specifically, a primary colorant (base ink) to be added so that the current visually or colorimetrically printed material color matches the visually or colorimetric target color of the previous OK printed matter. A color correction method is known in which the correction amount is determined by trial and error or the printing conditions are changed, and the amount of the coloring liquid (ink or the like) is corrected so that the color of the printed matter is constant.

In this type of color correction method, in order to reduce the load on a skilled person, instead of visual observation, when measuring the color of the colored liquid, the colored liquid is extracted into a colorimetric cell and the color is measured in a solution state. Technology that can be applied. For example, JP-A-61-
JP-A-56923 and JP-A-61-65123 disclose a method in which a light guide and a detection probe are immersed in a colored liquid for color measurement.

Japanese Patent Application Laid-Open No. 6-50819 discloses that
There is disclosed a method in which light is incident on a liquid surface of a colored liquid at a predetermined incident angle at the time of color measurement of a paint or the like having a high concealing property, and reflected light in a vertical direction is detected by a color sensor.

[0006]

However, in the above-described color correction methods, all of the colorimetric methods are inadequate for colorimetric measurement of a colored liquid, as described below, so that the quality of printed matter is degraded. There is a possibility that it will be done.

For example, in the case of a method in which the light guide is immersed, since the colorimetric cell cannot be rapidly washed, the coloring component adheres to the glass of the colorimetric cell and the complete coloring component adheres to the glass. Removal is difficult. In addition, since the color that has changed color is detected by the attached coloring component,
The color measurement result will be inaccurate.

Further, this method requires a wiping device for the detection probe, and may damage the tip of the probe due to repeated wiping. On the other hand, a method of detecting reflected light is limited to a coloring liquid having a high concealing property such as a paint, and cannot be applied to a coloring liquid having a high transparency such as gravure ink. The reason is that in the case of a colored liquid with a high concealing property, the color applied to a support such as paper and the color in a solution state are not affected by the color of the base, and the reflected light can be measured. However, in the case of a highly transparent colored liquid, the color applied to the support is different from the color in the solution state because the color of the base is affected.

The present invention has been made in consideration of the above-mentioned circumstances, and when a color change between a printed matter printed this time and a previous OK printed matter is detected, the amount of the colored liquid is controlled to be equal to or less than a control value. An object of the present invention is to provide a color correction device and a color correction method that can correct the amount of compounding and improve the quality of printed matter.

Another object of the present invention is to prevent the adhesion of a coloring component to a measuring cell and to apply it to a highly transparent coloring liquid.

[0011]

According to a first aspect of the present invention, there is provided an ink jet printer, comprising: a printing apparatus that prints a color liquid contained in a container repeatedly on a continuously supplied printing sheet; A color correction device for correcting the color of the liquid, the color liquid in the container is sampled, the liquid is irradiated with the liquid as it is, and one or both of the reflected and transmitted light is dispersed. A liquid monitor for measuring characteristics, a printed matter monitor for measuring the spectral reflectance of the colored liquid layer printed on the printing sheet, and a color value calculated from the spectral reflectance measured by the printed matter monitor. Based on the calculation result, a color change determining means for determining whether or not a color value has changed from the previous OK product, and when the color change determining means determines that the color value has changed, the color monitor is measured by the liquid monitor. A mixing ratio calculating means for calculating a mixing ratio of the coloring liquid from the value of the spectral characteristic so that a change amount of the color value from the previous OK product is equal to or less than a reference, and a change amount calculated by the mixing ratio calculating means as a weight. And a liquid supply unit for supplying a colored liquid or a transparent liquid into the container according to the corrected weight.

According to a second aspect of the present invention, in the color correction apparatus according to the first aspect, the liquid monitor section includes two transparent parallel flat plates which are arranged to face each other and whose interval is adjustable. A measuring cell having a liquid supply port and a liquid discharge port for passing the colored liquid between the parallel plates, and an incident optical system for allowing light to enter the colored liquid between the parallel plates. And a spectrophotometer for measuring one or both of the transmittance and the reflectance of the colored liquid between the parallel plates when light is incident by the incident optical system. .

Further, according to a third aspect of the present invention, when the coloring liquid contained in the container is repeatedly printed on a continuously supplied printing sheet, the color of the coloring liquid on the printing sheet is fixed. A color correction method for sampling a colored liquid in the container, irradiating the colored liquid with light as it is, and measuring one or both of reflected and transmitted light spectral characteristics. A liquid monitoring step, a printed matter monitoring step of measuring the spectral reflectance of the colored liquid layer printed on the printing sheet, and a color value calculated from the spectral reflectance measured by the printed matter monitoring step, based on the calculation result. A color change determination step for determining whether or not there is a change in color value from the previous OK product; and when the color change determination step determines that the color value has changed, measurement is performed by the liquid monitoring step. A mixing ratio calculating step of calculating a mixing ratio of the coloring liquid from the value of the spectral characteristic so that the change amount of the color value from the previous OK product is equal to or less than a reference; and the change amount calculated in the mixing ratio calculating step is weighted. And a blending correction step of supplying a colored liquid or a transparent liquid into the container according to the corrected weight.

As a specific measure for measuring the color of the colored liquid, for example, a colored liquid is filled between transparent parallel plates in a colored liquid in a container to form a thin film of the colored liquid. It is preferable to measure one or both of the reflectance and the transmittance of the thin film.

<Operation> Accordingly, the invention corresponding to claim 1 employs the above means, whereby the liquid monitor section samples the colored liquid in the container and emits light to the colored liquid as it is. Irradiate, measure the spectral characteristics of the reflected or transmitted light, the printed matter monitor unit measures the spectral reflectance of the colored liquid printed on the print sheet, the color change determination means,
The color value is calculated from the spectral reflectance measured by the print monitor, and based on the calculation result, the presence or absence of a change in the color value from the previous OK print is determined, and the color change determination unit determines that the color value has changed. When the determination is made, the correction compounding ratio of the colored liquid is calculated from the value of the spectral characteristic measured by the liquid monitor unit so that the amount of change in the color value from the previous OK product is equal to or less than the management value, and the calculated correction is calculated. Since the colored liquid or the transparent liquid is supplied into the container according to the corrected weight by the corrected weight calculating means for converting the amount into the weight, the quality control of the printed matter can be improved.

According to a second aspect of the present invention, as the liquid monitor section, there are provided two transparent parallel flat plates which are arranged opposite to each other and whose distance is adjustable, and the colored liquid passes between the parallel flat plates. A measuring cell provided with a liquid supply port and a liquid discharge port for causing the liquid to enter the colored liquid between the parallel plates; and an input optical system for inputting light to the colored liquid between the parallel plates. And a spectrophotometer for measuring one or both of the transmittance and the reflectance of the colored liquid. In this case, the coloring component can be prevented from adhering to the measuring cell by passing the coloring liquid through the measuring cell in which the fluororesin thin film layer is provided on the inner surface of the measuring cell. Further, by measuring the transmittance of transmitted light, it can be applied to a highly transparent colored liquid.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram illustrating a schematic configuration of a printing system to which a color correction device according to an embodiment of the present invention is applied, and FIG. 2 is a schematic diagram illustrating a concept of a print monitor unit applied to the color correction device. It is.

This color correcting apparatus includes a paper feed unit (1), four-color printing units (2a to 2d), a drying unit, a cooling / web path unit (3), and a folding unit. (Hereinafter referred to as printing ink) stored in tanks (containers, also referred to as ink pans) in printing units (2a to 2d) with respect to a web (winding paper) printing sheet (4) continuously supplied from ) Will be described as an example.

Specifically, a printing unit monitor unit (5) is arranged near the web printing sheet (4) between the drying unit and the cooling / web path unit (3), and each printing unit (2a to 2a)
The liquid monitoring units (6a to 6d) are arranged in d), respectively, and the arithmetic control unit (7) is provided between the two monitoring units (4, 6a to 6d).

Here, as shown in FIGS. 2 and 3, the printed matter monitor section (5) includes a light source section (8), a sensor (9), a scanning section (10), a colorimetric section (11), and a display section. (C12) and these light source units (8), sensors (9), scanning units (10),
A stabilizing power supply (13) for the colorimetric section (11) and the display section (12) is provided.

The light source section (8) includes a web print sheet (4).
For example, a halogen lamp that generates white light is used. However, instead of the halogen lamp, the light source section (8) may use a light source having a relatively wide emission wavelength range, such as a tungsten lamp or a xenon lamp.

The sensor (9) is arranged close to the web printing sheet (4) in the middle of the running after drying, and is scanned by the scanning unit (10) in the width direction W orthogonal to the running direction R of the web printing sheet (4). And has a function of detecting reflected light from the web print sheet (4) and providing a detection signal to the colorimetric unit (11). Note that the sensor (9) may be a fixed type instead of the scanning type, and the light source unit (8) and the sensor (9) may have an inclination of 0-45 degrees with respect to the sheet surface. The optical design is appropriately made.

The scanning section (10) is for scanning the sensor, and has a breaker (10a) connected to the stabilized power supply (13), a relay (10b) for scanning, and a sequencer (10c). And the control signal of the sensor from the sequencer (10c) to the RS232-C12 of the display unit (12).
a and the function of providing the sensor (9) via the SCSI (12b).

The colorimeter (11) measures the spectral reflectance of the reflected light based on the detection signal received from the sensor (9), and sends the measurement result to the display (12) and the operation controller (7). Has a function.

The display section (12) is for displaying the measurement results received from the colorimetric section (11), and for example, a general-purpose personal computer can be used.

The arithmetic control unit (7) has a function of giving an instruction for colorimetry to both the print monitor unit (5) and the liquid monitor units (6a to 6d) at the same time, and the measurement is performed by the print monitor unit (5). The color values such as L * a * b * values are calculated from the spectral reflectance, and the difference between the L * a * b * values from the previous printing lot (hereinafter also referred to as color difference) is calculated. And a function of determining that the color difference exceeds the upper limit of the standard as a failure and transmitting a failure detection signal to the liquid monitor units (6a to 6d).

Next, the configuration of each of the liquid monitor units (6a to 6d) will be described. Since each of the liquid monitor units (6a to 6d) has the same configuration except for the colors to be handled, one liquid monitor unit (6a to 6d) is used. 6a) will be described as a representative example.

As shown in FIG. 4, the liquid monitor section (6a) includes first and second flat glass sections (2) formed of two transparent parallel flat substrates which are arranged to face each other and whose interval is adjustable.
1, 22) and the first and second flat glass portions (2
A film forming apparatus (20) including a measuring cell in which a liquid supply port (23a) and a liquid discharge port (23b) for passing a colored liquid between 1, 2 and 22); and a film forming apparatus (20) The first and second flat glass portions (21,
22) An incident optical system for entering light into the colored liquid between the first and second flat glass portions (21, 22) when light is incident on the incident optical system. Spectrophotometer (31) for measuring the transmittance of light
And a computer that performs color correction based on the measurement result (32)
And

Here, the film forming apparatus (20) has a first flat glass portion (21) as a bottom portion, and stands upright on the periphery of the first flat glass portion (21). 23a) and a housing glass (23) provided with a liquid discharge port (23b), and a convex portion (2
A piston case (24) having a cylindrical shape with openings at both ends formed with 4a), and a lower opening (24b) provided to accommodate the housing glass (23) in the cylinder.
A protrusion (26a) is formed at the center of the outer wall, holding a slidable piston glass (25) on the inner wall of the housing glass (23) at the lower end and engaging with the piston case protrusion (24a). An upper and lower piston (26) slidable on a piston case projection (24a), and a piston case (24)
A lid member (27) is provided on the top and holds the outer wall on the rear end side of the upper and lower piston (26) so as to be able to move forward and backward, and a drive unit is provided for driving the upper and lower piston (26) to move forward and backward.

Here, the first flat glass portion (21), the housing glass (23), the piston glass (25) and the second flat glass portion (22) at the bottom of the piston glass are made of quartz glass, synthetic quartz glass or BK7 glass. And the like.

At least the first flat glass portion (2
1) and the second flat glass portion (22) disposed in parallel and opposed to each other may be in contact with each other as in the case of zero alignment of a gap or the like, and thus have sufficient hardness in addition to being transparent. It is preferable that the contact surfaces be formed smoothly.

The first and second flat glass portions 21 and
2. Housing glass (23) and piston glass (2)
5) is provided with an adhesion prevention layer (not shown) made of a fluororesin thin film (thickness of several nm to several tens nm) on the surface of the internal space (cell for measurement) in contact with the coloring liquid.

The liquid supply port (23a) and the liquid discharge port (23b) are formed so that the inner and outer peripheral portions of the housing glass (23) communicate with each other, and are arranged to face each other via the optical axis. I have. Liquid supply port (23
To a), one end of a first conduit (28a) for introducing, for example, a printing ink A as a coloring liquid is connected. The other end of the first conduit (28a) is connected via a check valve (29a) to an ink pan (30a) containing a printing ink A, for example, as a coloring liquid supply source.

On the other hand, one end of the second conduit (28b) is connected to the liquid discharge port (23b). The second conduit (28
The other end of b) is connected to a waste liquid ink pan (30b) via a check valve (29b).

The piston glass (25) is hollow inside and holds a spectrophotometer (31) described later.
The second flat glass portion (22) at the bottom of the piston glass is brought close to the first flat glass portion (21) by the lowering of the piston glass (25), and forms parallel flat plates with each other to form the first and second flat glass portions. A gap for forming a thin film of the coloring liquid (printing ink A) is formed between (21, 22). The value of the gap is, for example, between several microns and several tens of microns, and an appropriate value is selected in advance according to the concealing property of the ink A so that the transmitted light amount is at least a predetermined value or more. This is because, when the film thickness is constant, when the color of the ink A having a high concealing property is measured, the obtained spectral characteristics become inaccurate due to an insufficient amount of transmitted light. An appropriate value of the gap is considered to be about 5 to 20 microns in the case of gravure ink.

As the driving unit, a fluid pressure cylinder such as air for moving the vertical piston (26) up and down is used. In addition, the driving unit includes the first and second flat glass units (2
The stepping motor or the stepping motor is not limited to a fluid pressure cylinder as long as it has a performance capable of submicron position control formed in a desired micron unit (several μm to several tens μm) gap between (1, 2). A servo motor or the like may be used.

The hydraulic cylinder is an upper and lower piston (26)
A fluid pressure source (33) for supplying a fluid for driving the
An upper communication port (24c) formed above the convex portion (26a) to communicate the inner peripheral surface with the outer peripheral surface, and the convex portion (26).
b) a piston case (2) having a lower communication port (24d) formed below and communicating the inner peripheral surface and the outer peripheral surface.
4), an upper solenoid valve (34a) for communicating or blocking between the fluid pressure source (33) and the upper communication port (24c), and a connection between the fluid pressure source (33) and the lower communication port (24d). And a lower solenoid valve (34b) for communicating or shutting off.

That is, the fluid pressure cylinder has the same function as that of the function in which the fluid introduced from the fluid pressure source (33) pushes the upper and lower pistons (26) together with the projections (26a) by opening the upper solenoid valve (34a). It has a function of pushing up the upper and lower pistons (26) together with the projections (26a) by opening the lower solenoid valve (34b).

The piston case (24) has a position for detecting the upper and lower pistons (26) positioned at the lower limit and the upper and lower pistons (26) positioned at the upper limit, respectively, and sending them to a computer (32) to be described later. Sensor (35a, 35
b). The position of the upper and lower pistons (26) can be regulated based on the detection results of the position sensors (35a, 35b).

The incident optical system is the first optical system of the film forming apparatus (20).
A light source section (36) is provided below the flat glass section (21) and irradiates the colored liquid between the first flat glass sections (21) with light. As the light source section (36), a 100 W halogen lamp for generating white light and a light guide for introducing white light are used, but a tungsten lamp or a xenon lamp having a relatively wide emission wavelength range may be used. .

The spectrophotometer (31) is held in the piston glass (25), and is colored in the gap between the second flat glass portion (22) and the first flat glass portion (21) at the bottom of the piston glass. The grating and the CCD array have a function of detecting the amount of spectral light, measuring the spectral transmittance T (λ), and providing the measurement result to the computer (32) with respect to the transmitted light transmitted through the liquid.

The spectral transmittance T (λ) is about 400 n
The visible light region of m to 700 nm is measured at intervals of, for example, 20 nm. Further, the spectrophotometer 31 may use a filter instead of the grating, and may use a photomultiplier tube instead of the CCD.

The computer (32) holds the spectral transmittance T (λ) received from the spectrophotometer (31) in time series,
When a failure detection signal is received from the arithmetic and control unit 7, the spectral transmittance Tf (λ) of the colored liquid at the time of the failure determination is determined by the absorption coefficient Kf.
(Λ) and the ratio ΔTf (λ) / Rf between the spectral reflectances Rf (λ) and Tf (λ) of the printed matter at the time of the defect determination.
(Λ)｝ is determined as a conversion coefficient for converting the spectral reflectance into the spectral transmittance of the colored liquid. Next, the spectral transmittance value T0 (λ) of the ink of the previous OK print is predicted by multiplying the reflectance of the previous OK print by the conversion coefficient. Since the printing conditions of the printing press are not always kept at the same value, it is necessary to predict the ink transmittance value under the present conditions. Therefore, the predicted spectral transmittance value of the previous OK ink is actually different from the actually measured value. Next, a predicted absorption coefficient K0 (λ) of the previous OK ink is calculated from T0 (λ),
An additional correction amount ΔCi of the base ink to be additionally corrected in the container of the printing unit is calculated from the difference value with respect to Kf (λ). It has a color correction function for adding and correcting colors. The additional correction amount ΔCi is converted into an additional correction weight ΔWi using a measuring device or the like, and the base ink and the diluent in the external tank are added to the container of the printing unit via piping equipment.

The computer (32) is a function that can be omitted. The computer (32) controls the fluid pressure cylinder based on the detection results of the position sensors (35a, 35b), and regulates the lowering position or the rising position while controlling the lowering position or the rising position. A function may be provided in which the piston (26) is lowered before color measurement and is raised after color measurement is completed.

The lowering position of the upper and lower pistons (26) is actually located at the lowering limit because the second flat glass portion (22) is regulated by contact with the first flat glass portion (21). The position sensor (35a) for detecting the upper and lower pistons may be omitted, or may be modified so as to send a detection signal slightly before the lower limit.

Next, a color correction method using such a color correction device will be described with reference to the flowchart of FIG.

Now, in the liquid monitor sections (6a to 6d), it is assumed that the first and second flat glass sections 21 and 22 have an interval of several mm (ST1). By driving a not-shown vacuum pump or the like, the printing ink A in the ink pan (30a) flows into the measuring cell through the liquid supply port (23a), and passes between the first and second flat glass portions 21 and 22. The liquid is discharged from the liquid discharge port (23b) (ST2).

Next, the cylinder glass (25) is lowered by the fluid pressure cylinder (ST3), the printing ink A is crushed until a predetermined interval is reached, and the liquid is discharged while the printing ink A is formed into a desired thin layer of a micron unit. Port (23
Discharge from b).

As a result, in the film forming apparatus (20), a thin film of the printing ink A in micron units which always passes between the first and second glass portions 21 and 22 in a parallel plane is formed (ST4).

Thereafter, the liquid monitor units (6a to 6d)
Light is emitted from the light source section (36) to the printing ink A sampled from the ink pan (30a) and passing through the measuring cell. Further, the print monitor 5 irradiates light from the light source unit (8) onto the web print sheet (4) (ST5).
As a result, both monitor units (5, 6a to 6d) enter a state in which colorimetry is possible.

Here, the gravure rotary press starts printing, and repeatedly prints the printing ink contained in the container in each of the printing units (2a to 2d) on the continuously supplied web printing sheet (4). (ST6). At this time, the arithmetic control unit (7) periodically instructs the liquid monitor units (6a to 6d) and the printed material monitor unit (6a to 6d) to measure the spectral characteristics every predetermined printing length (or every predetermined time). 5) is given to both at the same time (ST7).

Upon receiving an instruction from the arithmetic and control unit (7), the liquid monitor units (6a to 6d) measure the spectral transmittance T (λ) of the transmitted light that has passed through the colored liquid, and obtain the obtained spectral transmittance. T (λ) and history information such as 100 meters (or measurement time) from the start of printing are stored as a set.

On the other hand, the print monitor unit (5) measures the spectral reflectance of the colored liquid layer (ink layer or the like) printed on the print sheet (ST8), and calculates the obtained spectral reflectance by the arithmetic control unit (7). Give to).

The arithmetic control unit 7 calculates an L * a * b * value as a color value from the spectral reflectance (ST9; color change judgment means), and calculates the L * a value measured in the previous OK printed matter.
The color difference from the * b * value is determined, and the presence or absence of a change in the L * a * b * value, that is, the quality of the printed matter, is determined based on whether the color difference exceeds the upper limit of the standard (ST10: color change determination unit). ).

The L * a * b * value corresponds to the color of the printed matter. As shown in FIG. 6, due to the influence of fluctuation factors such as ink change and printing condition change due to temperature change during the printing process, It fluctuates every moment, but it is desirable that it be as constant as possible.

The arithmetic control unit (7) calculates the current L * a * b *
When the value does not change, the quality of the printed matter is determined to be “good”, and the L * a * b * value and 10% from the start of printing are determined.
History information such as 0 meter or measurement time) is stored as a set (ST11).

The arithmetic control unit 7 calculates the current L * a * b
* When there is a change in the value, the quality of the printed matter is determined to be "defective", and a failure detection signal at the time of the failure determination is sent to the liquid monitor units (6a to 6d) (ST12).

Upon receiving the failure detection signal, the liquid monitor units (6a to 6d) measure the spectral transmittance Tf (λ) at the time of the failure determination based on the failure detection signal, and obtain the obtained spectral transmittance value. Is given to the arithmetic and control unit (7).

The liquid monitor sections (6a to 6d)
The spectral transmittance Tf (λ) of the colored liquid at the time of the defect determination is converted into an absorption coefficient Kf, and a conversion coefficient for converting the spectral reflectance into the spectral transmittance of the colored liquid is obtained (ST13; means for calculating a change in composition).

In general, for a liquid having high transparency, assuming that the thickness of the liquid is X, the absorption coefficient K and the transmittance T have the relationship of the following equation (1). K = −ln (T) / X (1) Here, since X is the film thickness at the time of measurement and is constant, the compounding ratio of the colored liquid and the corrected weight are calculated based on the difference in the absorption coefficient as described later. Therefore, the equation (1) may be replaced with the following equation (2) by omitting the coefficient 1 / X. K = −ln (T) (2)

This equation (2) shows that the transmittance T can be converted into an absorption coefficient K. That is, the liquid monitor units (6a to 6d) use the equation (2) to calculate the spectral transmittance T
(Λ) is converted to an absorption coefficient K (λ). Further, the spectral transmittance value T0 (λ) of the ink of the previous OK is predicted by multiplying the reflectance of the print of the previous OK by the conversion coefficient.

Subsequently, the amount of additional correction of the base ink to be additionally corrected in the container of the printing unit is calculated from the difference between the predicted absorption coefficient K0 (λ) and Kf (λ) of the OK ink using the equation (3). I do.

(K) mix = {Ci × (K) i} (3)

Here, Ci is the compounding amount of the i-th base ink supplied to a certain printing unit (2a), for example, and (K) i is the absorption coefficient of the i-th base ink. (K) mix is, for example, an absorption coefficient of a colored liquid (a mixed color solution in which the first to n-th base inks are mixed) in the container of the printing unit (2a).

Incidentally, the predicted absorption coefficient K0 of the previous OK ink
Assuming that the difference between (λ) and Kf (λ) is equal to the already calculated right-hand side of equation (3) {(Ci × (K) i)}, the left-hand side of equation (3) is replaced and Equation (4) is derived.

K0−Kf = {Ci × (K) i} (4)

Here, K0 = Σ (Ci × (K) i) Kf = Σ (Ci × (K) i) ΔCi: ink additional correction amount The liquid monitor units (6a to 6d) have two absorption coefficients K0 and The left side of equation (4) indicating the difference of Kf is calculated for each wavelength in the visible light region (ST14; blending change calculating means).

Next, the liquid monitor units (6a to 6d) use the least squares method and replace the left side of equation (4) with the right side of equation (4).
An additional amount ΔCi of each base ink is calculated so as to be equal to (ΔCi × (K) i)｝, and is converted into an additional corrected weight ΔWi using a measuring device or the like according to the calculation result (ST1).
5; means for calculating composition change).

Subsequently, the liquid monitor units (6a to 6d)
Each printing unit (2a to 2d) is installed from the piping system of the external tank according to the additional corrected weight ΔWi obtained by the least square method.
The base inks are additionally corrected (ST16; blending correction means).

As described above, the absorption coefficient Kf of the colored liquid in the printing units (2a to 2d) at the time of the defect determination is determined by the previous OK.
By correcting the blending amount of the coloring liquid so as to approach the absorption coefficient K0 of the above, it is possible to suppress the color fluctuation of the printing color on the web printing sheet (4).

Next, a specific example of this embodiment will be described. For example, an aqueous gravure ink (yellow, red, indigo, reducer) for building materials manufactured by Polytex Co., Ltd. is adjusted to a viscosity of 13 seconds with a # 4 Zahn cup, and printing is started with an ink mixed in an appropriate amount. .

The arithmetic control unit (7) periodically and simultaneously sends a colorimetric instruction to the liquid monitor units (6a to 6d) and the print monitor unit 5. The liquid monitor units (6a to 6d) apply the printing ink A of the container to the visible light region 400 according to the colorimetric instruction.
The print monitor unit (5) measures the color of the web print sheet (4) in the visible light range from 400 nm to 700 nm according to the color measurement instruction.
nm is measured at 20 nm intervals.

Immediately after the start of printing, the spectral transmittance T1 (λ) of the printing ink A1, which was determined to be defective from the magnitude of the color difference from the previous OK printed matter, was obtained. Color correction is performed based on the value.

The liquid monitor sections (6a to 6d) are
, The absorption coefficient K0 (λ) is determined from the spectral transmittance Tf (λ) at the time of failure determination, and the difference 両 between the two absorption coefficients for each wavelength. K0 (λ) -Kf (λ)} was determined. Thereafter, an additional correction amount ΔCi of the base ink is calculated, and a correction weight is calculated based on the result.

Here, the spectral transmittances To (λ), Tf
(Λ), the absorption coefficients K0 (λ), Kf (λ) and the value of the difference between the two absorption coefficients are as shown in FIG.

From the above measurement results, the added amount ΔCi of the base ink was 0.84% for yellow, 0.74% for red, and 0.59 for indigo.
% And reducer 5%. At this point, the ink weight in the container was 33 kg, so the additional weight ΔWi of each base ink was 0.28 kg for yellow, 0.24 kg for red,
The indigo was 0.19 kg and the reducer was 1.65 kg. As a result of modifying the blending amount of the coloring liquid based on the additional weight ΔWi, it was possible to reduce color fluctuation on the paper web print sheet 4.

In the same manner, by repeating such color correction at the time of the defect determination, it is possible to suppress the color variation of the printed material color between print lots.

As described above, according to the present embodiment, the liquid monitor units (6a to 6d) irradiate the printing ink A extracted from the container with light and measure the spectral characteristics of the transmitted light.
The print monitor 5 measures the spectral reflectance of the printing ink A printed on the web print sheet (4), and the arithmetic control unit (7) calculates the color value from the spectral reflectance and determines
It is determined whether or not the color value has changed from the K print, and when it is determined that the color value has changed, the liquid monitor units 6a to 6d perform printing in the container based on the value of the spectral transmittance T (λ). Calculate the additional correction amount ΔCi of the mixing amount of ink A, and calculate ΔCi
The base ink (colored liquid) or the reducer (diluent) is supplied into the container according to the additional weight ΔWi calculated in accordance with the following formula. The blending amount can be corrected so as to be the color of the printed matter of the previous OK, and the variation of the printed color between lots can be reduced.

In addition, in a toning method called computer color matching of a well-known technique, each base ink is adjusted so that the absorption coefficient (K) mix of the colored liquid of the printing unit matches the target absorption coefficient Ko of the colored liquid. Is calculated.

On the other hand, in the present embodiment, the CCM
(Computer ColorMatching)
The difference between the predicted absorption coefficient K0 (λ) of the colored liquid in the previous OK and the absorption coefficient Kf (λ) at the time of the failure determination {K0 (λ) −Kf (λ)} The addition correction amount ΔCi of the blending amount of the coloring liquid is calculated using the multiplication method.

The liquid monitor sections (6a to 6b) have two transparent first and second flat glass sections (21, 22) which are arranged opposite to each other and whose distance is adjustable.
A measuring cell having a liquid supply port (23a) and a liquid discharge port (23b) for allowing the printing ink A to pass between the flat glass portions (21, 22); and a flat glass portion (21, 22). An incident optical system for allowing light to enter the printing ink A between the two, and a spectrophotometer (31) for measuring the transmittance of transmitted light passing through the printing ink A when the light is incident by the incident optical system. ), The colored liquid is passed through the measuring cell to prevent the coloring component from adhering to the measuring cell, and by measuring the transmittance of the transmitted light, highly transparent coloring is achieved. It can also be applied to liquids.

Further, the ink pan (30
Since the printing ink A of (a) can be automatically supplied to the film forming apparatus (20), the color measurement can be performed on the site side without the need for manual labor. It can be performed stably with high accuracy.

The first and second flat glass portions (21,
22) are brought into contact with each other to adjust the zero position, and then a constant gap is formed, so that even when the relative positional relationship or the like in the colorimetric cell changes with time, an error occurs in the film thickness control. Since this does not occur, the reliability of the film thickness control can be improved.

The first and second flat glass portions (21,
As for 22), since the contact surfaces are formed to be smooth, the effect of the present embodiment can be easily and reliably exhibited.

Further, the first and second flat glass portions (2
1, 22), the housing glass (23) and the piston glass (25) are made of quartz glass, synthetic quartz glass or BK.
Since it is formed of a transparent material such as 7 glass, the effects of the present embodiment can be easily and reliably achieved.

The first and second flat glass portions (21,
22), since the housing glass (23) and the piston glass (25) are provided with an anti-adhesion layer made of a fluororesin thin film on the surface in contact with the printing ink A, the cleaning property can be increased as compared with the conventional case.

Further, since the fluid pressure cylinder is provided as the driving means, the effects of the present embodiment can be easily and reliably exhibited.

Further, when position sensors (35a, 35b) for detecting the lower limit position and the upper limit position of the upper and lower pistons (26) are provided, the positions of the upper and lower pistons (26) are automatically regulated. As a result, operability can be improved.

In the above embodiment, the case where the liquid monitor units (6a to 6d) calculate the additional correction amount ΔCi of the printing ink A to correct the blending amount has been described. However, the present invention is not limited to this. Even if (7) is configured to correct the blending amount by calculating the additional amount ΔCi of the colored liquid, the same effect can be obtained by implementing the present invention in the same manner. That is, data processing other than measurement of spectral characteristics such as transmittance and reflectance (color change determining means, blending change calculating means, blending correcting means)
May be modified so as to be assigned to any of the liquid monitor sections (6a to 6d), the printed matter monitor section (5), and the arithmetic control section (7). , Within the scope of the present invention.

Further, from the viewpoint of making the light uniform, on the incident optical axis between the light source section (36) and the first flat glass section (31) or on the second flat glass section (22) and the spectrophotometer ( 31), the present invention can be implemented in the same manner and have the same effect even if a well-known integrating sphere (for example, Otsuka Electronics Co., Ltd.) is interposed on the transmitted optical axis. In addition,
The integrating sphere is preferably provided integrally with the container from the viewpoint of improving the colorimetric accuracy by taking in the transmitted light transmitted through the colored liquid 180 degrees while causing scattering and absorption, etc., and improving the colorimetric accuracy.

Further, the case where the spectrophotometer (31) measures the spectral transmittance has been described. However, the present invention is not limited thereto, and the spectrophotometer (31) measures the spectral absorption intensity or the spectral reflectance (for the case of the spectral reflectance measurement). The present invention can be implemented in the same manner and the same effect can be obtained by a configuration that measures spectral characteristics such as a spectrophotometer (31) and a light source section (36) are disposed on the same side.

Further, the case where the spectrophotometer 31 is held in the piston glass (25) and the light source section (36) is disposed below the first flat glass section (21) has been described. Even if the arrangement of the spectrophotometer (31) and the light source section (36) is reversed, the same effect can be obtained by implementing the present invention in the same manner.

The spectrophotometer (31) and the light source (3)
6) is disposed on a different side from the colored liquid to measure the transmitted light. However, the present invention is not limited to this, and the spectrophotometer (31) and the light source (36) are viewed from the colored liquid. Even if it is arranged on the same side and the spectrophotometer (31) is modified to measure the reflected light from the colored liquid, the present invention can be implemented in the same manner and the same effect can be obtained.

Further, the coloring liquid is sampled so as to be taken out of the ink pan (30a), and the sample is taken out of the ink pan (30a).
The case where the measurement is performed outside the a) has been described. However, the present invention is not limited to this, and the present invention can be similarly implemented in a configuration in which the colored liquid is sampled in the ink pan (30a) and measured inside the ink pan (30a). The same effect can be obtained.

In addition, the present invention can be variously modified and implemented without departing from the gist thereof.

[0096]

As described above, according to the present invention, when the color change of the printed printed matter is detected, the compounding amount of the coloring liquid can be corrected to the state before the color change, and the quality of the printed matter can be improved. The obtained color correction device and color correction method can be provided.

In addition, the present invention can be applied to a highly transparent colored liquid while preventing the coloring component from adhering to the measuring cell.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating a schematic configuration of a printing system to which a color correction device according to an embodiment of the invention is applied.

FIG. 2 is a schematic diagram showing the concept of a print monitor in the embodiment.

FIG. 3 is an exemplary block diagram showing the configuration of a print monitor in the embodiment.

FIG. 4 is a schematic diagram showing a configuration of a liquid monitor unit according to the embodiment.

FIG. 5 is a flowchart for explaining the operation in the embodiment.

FIG. 6 is an exemplary view for explaining changes in color values in the embodiment.

FIG. 7 is a diagram showing a data table for explaining a specific example in the embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Paper feed part 2a-2d ... Printing unit 3 ... Cooling / web path part 4 ... Web printing sheet 5 ... Printing part monitor part 6a-6d ... Liquid monitor part 7 ... Calculation control part 8, 36 ... Light source part 9 ... Sensor DESCRIPTION OF SYMBOLS 10 ... Scanning part 11 ... Colorimetric part 12 ... Display part 13 ... Stabilized power supply 20 ... Film forming apparatus 21, 22 ... Flat glass part 23 ... Housing glass 23a ... Liquid supply port 23b ... Liquid discharge port 24 ... Piston case 24a, 26a ... convex part 24b ... opening part 24c, 24d ... communication port 25 ... piston glass 26 ... upper and lower piston 27 ... lid member 28a, 28b ... conduits 29a, 29b ... check valves 30a, 30b ... ink pan 31 ... spectrophotometer 32 ... Computer 33: Fluid pressure source 34a, 34b: Solenoid valve 35a, 35b: Position sensor A: Printing ink

Continued on the front page (72) Inventor Akihiro Tsukada 1-5-1, Taito, Taito-ku, Tokyo Toppan Printing Co., Ltd. F-term (reference) 2C250 EA23 EB16 EB43 2G020 AA08 DA02 DA03 DA04 DA12 DA22 DA31 DA34 DA35 DA62

Claims (3)

[Claims] 1. A color correction device for correcting the color of a colored liquid on a printing sheet to a constant value when repeatedly printing a colored liquid contained in a container on a continuously supplied printing sheet. The colored liquid in the container is sampled, and the liquid is irradiated with light as it is and any one of the reflected or transmitted light is irradiated.
A liquid monitor for measuring one or both of the spectral characteristics, a printed matter monitor for measuring the spectral reflectance of the colored liquid layer printed on the printing sheet, and a color value from the spectral reflectance measured by the printed matter monitor. Calculating, based on the calculation result, a color change determining means for determining the presence or absence of a change in the color value from the previous OK product; and when the color change determining means determines that the color value has changed, the liquid monitor The mixing ratio calculating means for calculating the mixing ratio of the coloring liquid from the value of the spectral characteristic measured by the section so that the amount of change in the color value from the previous OK product is equal to or less than the reference, and the mixing ratio calculating means. A correction weight calculating means for converting the changed amount into a weight; and a liquid supply means for supplying a colored liquid or a transparent liquid into the container according to the corrected weight. 2. A color correcting apparatus according to claim 1, wherein said liquid monitor section has two transparent parallel flat plates which are arranged opposite to each other and whose distance is adjustable, and said liquid monitor section is provided between said parallel flat plates. A measuring cell having a liquid supply port and a liquid discharge port for passing a colored liquid, an incident optical system for incident light on the colored liquid between the parallel flat plates, and light incident by the incident optical system. And a spectrophotometer for measuring either one or both of the transmittance and the reflectance of the colored liquid between the parallel flat plates. 3. A color correcting method for correcting a color of a coloring liquid on a printing sheet to a constant value when repeatedly printing a coloring liquid contained in a container on a continuously supplied printing sheet. The colored liquid in the container is sampled, and the liquid is irradiated with light as it is and any one of the reflected or transmitted light is irradiated.
A liquid monitoring step of measuring one or both of the spectral characteristics,
A color value is calculated from the spectral reflectance measured by the printed matter monitoring step and the printed matter monitoring step for measuring the spectral reflectance of the colored liquid layer printed on the print sheet, and based on the calculation result, A color change determining step of determining whether or not there is a change in the color value of the color image; and determining that the color value has changed by the color change determining step. A mixing ratio calculating step of calculating the mixing ratio of the colored liquid such that the amount of change in the color value is equal to or less than a reference, a corrected weight calculating step of converting the amount of change calculated in the mixing ratio calculating step into a weight, A color correction method for supplying a colored liquid or a transparent liquid into the container according to the corrected weight.